/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.propertyeditors;

import java.beans.PropertyEditorSupport;
import java.text.DateFormat;
import java.text.ParseException;
import java.util.Date;

import org.springframework.lang.Nullable;
import org.springframework.util.StringUtils;

/**
 * Property editor for {@code java.util.Date},
 * supporting a custom {@code java.text.DateFormat}.
 *
 * <p>This is not meant to be used as system PropertyEditor but rather
 * as locale-specific date editor within custom controller code,
 * parsing user-entered number strings into Date properties of beans
 * and rendering them in the UI form.
 *
 * <p>In web MVC code, this editor will typically be registered with
 * {@code binder.registerCustomEditor}.
 *
 * @author Juergen Hoeller
 * @see java.util.Date
 * @see java.text.DateFormat
 * @see org.springframework.validation.DataBinder#registerCustomEditor
 * @since 28.04.2003
 */
public class CustomDateEditor extends PropertyEditorSupport {

    private final DateFormat dateFormat;

    private final boolean allowEmpty;

    private final int exactDateLength;


    /**
     * Create a new CustomDateEditor instance, using the given DateFormat
     * for parsing and rendering.
     * <p>The "allowEmpty" parameter states if an empty String should
     * be allowed for parsing, i.e. get interpreted as null value.
     * Otherwise, an IllegalArgumentException gets thrown in that case.
     *
     * @param dateFormat DateFormat to use for parsing and rendering
     * @param allowEmpty if empty strings should be allowed
     */
    public CustomDateEditor(DateFormat dateFormat, boolean allowEmpty) {
        this.dateFormat = dateFormat;
        this.allowEmpty = allowEmpty;
        this.exactDateLength = -1;
    }

    /**
     * Create a new CustomDateEditor instance, using the given DateFormat
     * for parsing and rendering.
     * <p>The "allowEmpty" parameter states if an empty String should
     * be allowed for parsing, i.e. get interpreted as null value.
     * Otherwise, an IllegalArgumentException gets thrown in that case.
     * <p>The "exactDateLength" parameter states that IllegalArgumentException gets
     * thrown if the String does not exactly match the length specified. This is useful
     * because SimpleDateFormat does not enforce strict parsing of the year part,
     * not even with {@code setLenient(false)}. Without an "exactDateLength"
     * specified, the "01/01/05" would get parsed to "01/01/0005". However, even
     * with an "exactDateLength" specified, prepended zeros in the day or month
     * part may still allow for a shorter year part, so consider this as just
     * one more assertion that gets you closer to the intended date format.
     *
     * @param dateFormat DateFormat to use for parsing and rendering
     * @param allowEmpty if empty strings should be allowed
     * @param exactDateLength the exact expected length of the date String
     */
    public CustomDateEditor(DateFormat dateFormat, boolean allowEmpty, int exactDateLength) {
        this.dateFormat = dateFormat;
        this.allowEmpty = allowEmpty;
        this.exactDateLength = exactDateLength;
    }

    /**
     * Format the Date as String, using the specified DateFormat.
     */
    @Override
    public String getAsText() {
        Date value = (Date) getValue();
        return (value != null ? this.dateFormat.format(value) : "");
    }

    /**
     * Parse the Date from the given text, using the specified DateFormat.
     */
    @Override
    public void setAsText(@Nullable String text) throws IllegalArgumentException {
        if (this.allowEmpty && !StringUtils.hasText(text)) {
            // Treat empty String as null value.
            setValue(null);
        } else if (text != null && this.exactDateLength >= 0 && text.length() != this.exactDateLength) {
            throw new IllegalArgumentException(
                    "Could not parse date: it is not exactly" + this.exactDateLength + "characters long");
        } else {
            try {
                setValue(this.dateFormat.parse(text));
            } catch (ParseException ex) {
                throw new IllegalArgumentException("Could not parse date: " + ex.getMessage(), ex);
            }
        }
    }

}
